Changes in Several Traits of Oats Caused by Selection for Vegetative Growth Rate*

Growth rate and harvest index are the primary components that cause variation in gram yield or oats it growth duration of the crop is fixed as it is in mid western USA. Because harvest index for oats in that region has been optimized 45 %, growth rate is the only remaining trait for improving grain yield. F₂ derived oat lines from inter- (Avena sativa L. ×A. Sterilis L.) and intraspecific mating (among A. sativa cultivars) in F₃ were selected for vegetative growth rate at maturity (GRM) with an intensity of 8.3%. Predicted genetic gain was 21.5% for GRM, and actual gain was 7%. Changes in grain, biological, and straw yields were higher than gains in GRM when expressed as percentages of the oat population means. Predicted genetic gains were very low for traits unrelated or negatively associated with GRM such as heading data and harvest index. This study suggests that indirect improvement can be made for gain, biological, and straw yields by selecting for GRM.     

Harvest index increase during seed growth of field pea

Harvest index during seed growth has been reported to increase linearly with time for many crop species. Although the rate of harvest index increase was generally stable across experiments within a species, there are indications that it is sensitive to variations in temperature. The objective of the present study was to compare the harvest index increase for field pea (Pisum sativum L.) across 31 experiments that included a wide range of temperature environments. The change in harvest index within each experiment was well described by a linear increase with time but there was considerable variability among experiments. The increase in harvest index was also calculated as a function of thermal time after flowering. The variability was only marginally reduced. Use of thermal time was, however, superior in identifying a common point for the initiation of seed growth among the experiments.     

Variation in Rate and Duration of Growth Among Spring Barley Cultivars1

Ten two-rowed spring barley cultivars (Hordeum vulgare L.) were evaluated for growth parameters, i.e. crop growth rate, crop growth duration, grain filling rate, grain filling duration, vegetative growth rate, vegetative growth duration, single caryopsis filling rate, single caryopsis filling duration. Field studies were conducted on a sandy loam at Hohenschulen, Northern Germany with three levels of nitrogen fertilization and three sowing rates in 1986 to 1988. Cultivar effects were observed for all growth parameters except for crop growth rate and vegetative growth rate. But only crop growth duration n and grain filling duration showed positive correlations with grain yield. No growth rate parameter was related to yield. Biomass was correlated to crop growth duration and not to crop growth rate, while average caryopsis weight was strongly related to caryopsis filling rate and only moderately to caryopsis filling duration. Comparing grain filling rate and duration to individual caryopsis filling rate and duration, only grain filling rate and duration appeared to be relevant to grain yield. Since genetic variability for crop growth rate was lacking in the spring barley material tested, further improvement of yield would only result from increase in harvest index and/or longer crop growth duration.     

Sugarcane Breeding Institute,Coimbatore, India Effect of Different Levels of Drought during the Formative Phase on Growth Parameters and its Relationship with Dry Matter Accumulation in Sugarcane

A field experiment was conducted at Coimbatore (11° N, 77° E), India during the 1996 and 1997 crop seasons, using four commercial sugarcane varieties (Co 8021, Co 419, Co 8208 and Co 6304), to study the effect of three levels of drought (severe, moderate and control) during the formative phase (60–150 days after planting) on growth determinants and their relationship with dry matter accumulation. The reduction in dry matter content was 60.8, 52.4 and 25.9 % in severe drought and 46.3, 36.3 and 15.1 % in moderate drought at the ends of the formative, grand growth and maturity phases, respectively. High net assimilation rate, optimum leaf area index, high crop growth rate and an early shift in dry matter allocation to the stem were found to be desirable for higher biomass production, especially under water‐limited drought conditions. Measurement of growth parameters such as net assimilation rate, relative growth rate, leaf area index and leaf area duration under drought and crop growth rate and stalk elongation rate under normal irrigated conditions, particularly during the formative phase, might help to predict total dry matter at harvest. Leaf area ratio was not found to correlate with total dry matter at harvest in either drought or normal irrigated conditions.     

Physiological Basis of Yield in Moth Bean [Vigna aconitifolia (Jacq.) Marechal] Under Rainfed Conditions

Physiological analysis of yielding ability in moth bean varieties under rainfed condition revealed that in spite of sufficient amount of dry matter production, the crop is a poor seed yielder. Late varieties produced higher amounts of dry matter and seed. The low yield in this crop is owing to low net assimilation rate (NAR) during the reproductive phase and poor migration coefficient of assimilates towards seeds. Leaf area expansion was maximum during reproductive phase. Stomatal components were not evident to limit the NAR under rainfed condition. Varietal differences were observed with respect to transpiration. Temporal variations in leaf water potential, osmotic potential and pressure potential were recorded. It is concluded that in moth bean the improvement in seed yield is possible by increasing current photosynthetic rate during the reproductive phase and can be achieved by changing the crop canopy structure for better utilization of light. Effort should also be made to improve harvest index in this crop.     

Indentification of strong and weak yield determining components of winter oilseed rape compared with winter wheat

Yield formation of winter oilseed rape was compared with that of winter wheat in terms of absorption of PAR, radiation use efficiency and harvest index by means of crop growth simulation. Cumulative incoming PAR from April 15 until maturity, cumulative absorption of PAR, radiation use efficiency and harvest index were lower for winter oilseed rape compared with winter wheat. To improve potential seed yield of winter oilseed rape, a crop type with increased cumulative absorption of PAR, radiation use efficiency and harvest index is desirable.     

郑单958与先玉335黄淮海北部物候期特点分析

【研究目的】为了实时掌握夏玉米在黄淮海北部生长发育进程,综合评价环境因素对玉米生长发育的影响,调查分析了郑单958与先玉335在北纬37°53′、东经115°42′的物候期特征。夏播玉米郑单958与先玉335播种后6d出苗,生育期间为111d,灌浆期持续66d,叶片展开速率和灌浆速率随温度升高而加速,收获前6d（10月5-11日期间）,郑单958与先玉335产量贡献率分别达6.61%和4.20%。【结论】分析结果认为,黄淮海区域属于一年两熟种植模式,黄淮海北部夏玉米一般不能达到完熟收获。选用中早熟品种,及早抢播、适时晚收,保证玉米充足的有效积温和授粉后充足的灌浆时间可以显著提高玉米产量。     

再生稻需氮特性和分次施氮的研究

本文着重探讨了不同施氮水平下促芽肥与长苗肥对再生稻氮素营养、生长发育和产量形成的影响。     

The Effect of Planting Date and Plant Density on Potassium and Magnesium Uptake and Harvest by Brussels Sprouts

The effects of planting date and plant density on potassium (K) and magnesium (Mg) uptake and harvest by Brussels sprouts ( Brassica oleracea var. gemmifera ) were studied in field experiments. Crop potassium concentration generally decreased towards harvest, but the pattern in potassium concentration during crop growth differed between planting dates. Plant density in the range of 2.7–4.4 plants m⁻² had no effect on crop potassium concentration. The amount of potassium in the crop at harvest decreased with a delay in planting, but was not influenced by plant density. Mainly depending on the planting date, around 100–200 kg potassium ha⁻¹, or approximately 40–50 % of the potassium in the crop at harvest, is removed from the field with the product. Averaged over treatments and years, potassium concentration in the (fresh) product was 5.2 kg ton⁻¹. The amount of magnesium in the crop at harvest decreased with a delay in planting. Depending on the planting date, uptake at harvest was 10–17 kg magnesium ha⁻¹. Plant density had no effect on this amount. On average per ton (fresh) product, 0.20 kg of magnesium was removed from the field.     

Growth Analysis of Onion (Allium cepa L.) in Relation to Irrigation and Nitrogen Fertilization

Studies were carried out at the Indian Institute of Horticultural Research, Bangalore during winter seasons of 1982—83 and 1983—84 to analyse the growth rhythm of onion in relation to irrigation and N fertilization. It was observed that irrigation at 0.45 to 0.65 bar soil water potential recorded higher dry matter accumulation and distribution, leaf area index (LAI), leaf area duration (LAD), leaf area ratio (LAR) and crop growth rate (CGR) during most of the stages, while net assimilation rate (NAR) and relative growth rate (RGR) were not markedly affected. Highest harvest index was noticed with irrigation at 0.65 bar.
Nitrogen fertilization significantly increased dry matter accumulation and distribution into different parts, LAI, LAD, LAR, CGR and harvest index. Although NAR and RGR showed an increasing trend with N fertilization, the effect was not significant during most of the stages. There was no significant interaction between soil water potential and N fertilization on any of the growth parameters.     

Influence of Soil Moisture on Growth, Water Use and Yield of Mustard

A field experiment was conducted to study the influence of soil moisture on growth, water use and yield of mustard ( Brassica juncea L. cv. Rai 5 ). Two soil moisture regimes were rainfed and irrigated at 10 days interval throughout the growing season. The total amount of water received as irrigation was 110 mm and as rainfall was 15 mm. Total dry matter per unit ground area, leaf area index (LAI), crop growth rate (CGR) and net assimilation rate (NAR) were increased and leaf area ratio (LAR) and specific leaf area (SLA) were decreased by irrigation. Chlorophyll content and relative leaf water content (RLWC) were increased by irrigation, but proline content was greater in the rainfed crop at both the flowering and pod-filling stages. Time taken to first flowering, duration of flowering, number of seeds/pod and harvest index were unaffected by irrigation. Plant height at harvest, number of pods/plant, seed yield and oil content of seeds were increased and 1000-seed weight was decreased by irrigation. The consumptive use of water increased with an increase in water supply, but the water use efficiency (WUE) was decreased.     

不同类型玉米收割机对籽粒收获质量的影响评价

选择3种不同类型的玉米籽粒收割机和7个不同基因型玉米品种,开展玉米籽粒机收收获质量影响因素研究,探索不同类型收割机对不同基因型玉米籽粒收获质量的影响,以期为玉米籽粒收获收割机的选择和玉米籽粒机收技术的推广提供依据.根据试验取得的数据,不同基因型玉米品种的主要特征中稳住高、密度、穗粒数、单产分别对玉米籽粒破碎率、损失率、...     

Screening chickpea for adaptation to water stress: Associations between yield and crop growth rate

Robust associations between yield and crop growth rate in a species-specific critical developmental window have been demonstrated in many crops. In this study we focus on genotype-driven variation in crop growth rate and its association with chickpea yield under drought. We measured crop growth rate using Normalised Difference Vegetative Index (NDVI) in 20 diverse chickpea lines, after calibration of NDVI against biomass accounting for morphological differences between Kabuli and Desi types. Crops were grown in eight environments resulting from the combination of seasons, sowing dates and water supply, returning a yield range from 152 to 366 g m⁻². For both sources of variation – environment and genotype – yield correlated with crop growth rate in the window 300 °Cd before flowering to 200 °Cd after flowering. In the range of crop growth rate from 0.07 to 0.91 g m⁻² °Cd⁻¹, the relationship was linear with zero intercept, as with other indeterminate grain legumes. Genotype-driven associations between yield and crop growth rate were stronger under water stress than under favourable conditions. Despite this general trend, lines were identified with high crop growth rate in both favourable and stress conditions. We demonstrate that calibrated NDVI is a rapid, inexpensive screening tool to capture a physiologically meaningful link between yield and crop growth rate in chickpea.     

有机复合栽培基质对小麦施肥效应研究

为提高农林废弃物的再利用率,减少农作物栽培对施肥的依赖,以农林废弃物堆肥发酵基质为栽培基质,通过采用田间对比试验的方法,对冬小麦生长进行肥效对比试验。结果表明：与普通小麦肥以及化肥相比,有机复合栽培基质对小麦增长促进作用显著,小麦平均穗长比不施肥增长8.90%,比施化肥增长5.85%,比单施普通小麦肥增长5.49%;小麦平均穗数比不施肥增长40.79%,比施化肥增长17.11%,比单施普通小麦肥增长2.63%;小麦平均单产量比不施肥增长34.78%,比施化肥增长7.89%,比单施普通小麦肥增长2.01%。该研究可为农林废弃物在作物栽培方面的合理利用提供参考。     

Cassava (Manihot esculenta Crantz) Growth Indices, Root Yield and its Components in Upland and Inland Valley Ecologies of Sierra Leone

Cassava is predominantly an upland crop that is also cultivated in inland valley swamps (IVS). Identifying physiological traits that can withstand excess moisture stress can aid in the selection and use of stable cassava cultivars in IVS. Three cassava cultivars were evaluated for growth and yield in the upland and IVS ecologies in the 1993–94 crop seasons using a randomized complete block design. In the upland, 80/40 outyielded 87/29 and 'coco', while in the IVS, 87/29 had the highest yield. Highest yielding cultivars in each ecology also had the highest tuberous root bulking rate (TBR), dry matter (DM) production, crop growth rate (CGR), relative growth rate, net assimilation rate (NAR), leaf area index, leaf production rate and leaf life. Positive correlations between these parameters and tuberous root yield were noted. High yield of 87/29 in IVS was partly due to its low tuberous root rotting. High root rotting in 80/40 was partly as a result of the greater depth of tuberous roots in the soil (0.3–0.6 m) as compared to the other cultivars (0.15–0.3 m) where roots were in contact with stressful water levels earlier than others. The yield and yield components, growth and leaf characters were all drastically reduced when the cultivars were grown in IVS as compared to upland. For example, root yields of 'coco', 87/29 and 80/40 were reduced by 53 %, 60 % and 92 %, respectively, in IVS. Selection of cassava cultivars with longer leaf life and leaf area maintenance leading to high CGR, TBR, NAR and harvest index (in IVS and upland), coupled with a shallow tuberous root formation zone (in IVS) can give higher root and leaf yields in the two ecologies.     

The Effect of Damage to the Root System Caused by Inter-Row Cultivation on Growth of Maize

Inter-row cultivation of a weed-free maize crop may affect yield. This study was done to establish whether inter-row cultivation damages crop roots in maize ( Zea mays L.) and to assess the effect of root pruning on growth and yield. In 1986 and 1987 inter-row cultivation and root cutting treatments were applied to field-grown maize crops in three experiments. Growth analysis revealed that the crop responded differently to the treatments in each trial. Measuring xylem exudate shortly after application of the treatments as an estimator of root damage proved useful in explaining crop responses. In one experiment no root damage occurred and crop growth was not affected. When root damage did occur (in the other two experiments), dry matter yield 3 weeks after treatments was found to be related to xylem exudate yield shortly after the treatments. A reduction of xylem exudate of 1 g/h per plant was associated with a reduction of 360 to 700 kg/ha in whole plant dry matter. In one of these experiments the effect of root damage in whole plant dry matter yield remained until final harvest; in the other experiment all treatments had similar yields at final harvest.     

Effects of harvest management on growth dynamics, forage and seed yield in berseem clover

Berseem clover (Trifolium alexandrinum L.) is an annual forage crop widely grown in Mediterranean environments. However, there is little information available on the patterns of accumulation and partitioning of assimilate in berseem and how this varies with harvest management, plant ontogeny or is influenced by genotype. Field experiments were conducted in Foggia (Italy) during three growing seasons (1991–92, 1992–93 and 1993–94), with the aim of evaluating the effects of different harvest managements on growth dynamics, forage yield and seed yield of one population of Egyptian (cv. ‘Giza 10’) as well as Italian (cv. ‘Sacromonte’) origin. Cutting treatments were applied at three different plant ages: sixth internode elongation (A), early flowering (B), and uncut control (C). The growth and development of the shoot and root systems were followed by destructive harvests made at about 5-day intervals during 9 weeks in spring in all treatments. Seasonal growth pattern, determined as dry matter accumulation, forage yield and seed production were greatly influenced by harvest management. The maximum value (20.5 g per plant on average) of dry weight was reached at about 250 days after sowing for treatment C. Defoliation induced a decrease of crown and root dry matter, however, as shown by the allometric relationships, the growth of roots and shoots was closely correlated and in most cases, shoot growth was higher than root growth and stem relative growth rate (RGR) was higher than leaf RGR. Berseem clover is a defoliation-tolerant species because after cutting, regrowth was accompanied by higher values of leaf-stem ratio (LSR), RGR and stem elongation rate (SER) than in control plants. The highest value for total forage yield (1.6 Kg m⁻²) and seed yield (60.5 g m⁻²) were obtained in treatment B and A, respectively. Plants cut at the sixth internode elongation showed a good seed yield and a small decrease (15%) in total forage yield as regards treatment B. Therefore, treatment A appeared the most favourable for obtaining double utilization (forage and seed yield) in a berseem crop. Berseem plants were greatly influenced by harvest treatments applied, but the response did not vary according to the genetic characteristics of the two cultivars examined.     

Field Observations on Interactions between Orobanche cernua Loefl. and Bidi Tobacco in Nipani, India

Interactions between Orobanche cernua and bidi tobacco were recorded in naturally infested tobacco fields at Nipani, India. At harvest, most broomrapes occurred in clusters of 4–9 spikes per tobacco plant. The effects of broomrapes became visible at 50 days after transplanting tobacco and were mainly caused by a reduction of the growth rate of the tobacco plant and not by shortening the growth period. The tobacco crop grew exponentially until 60 days and thereafter linearly in the period 60–140 days after transplanting. From 140 days onwards the growth of the crop became truncated. The reduction in tobacco yields depended on the number of broomrapes per tobacco plant. Individual broomrape spikes were lower in dry weight when more spikes occurred per tobacco plant.     

Relay-intercropped forage legumes help to control weeds in organic grain production

In organic grain production, weeds are one of the major limiting factors along with crop nitrogen deficiency. Relay intercropping of forage legume cover crops in an established winter cereal crop might be a viable option but is still not well documented, especially under organic conditions.Four species of forage legumes (Medicago lupulina, Medicago sativa, Trifolium pratense and Trifolium repens) were undersown in six organic wheat fields. The density and aerial dry matter of wheat, relay-intercropped legumes and weeds were monitored during wheat-legume relay intercropping and after wheat harvest until late autumn, before the ploughing of cover crops.Our results showed a large diversity of aerial growth of weeds depending on soil, climate and wheat development. The dynamics of the legume cover crops were highly different between species and cropping periods (during relay intercropping and after wheat harvest). For instance, T. repens was two times less developed than the other species during relay intercropping while obtaining the highest aerial dry matter in late autumn. During the relay intercropping period, forage legume cover crops were only efficient in controlling weed density in comparison with wheat sole crop. The control of the aerial dry matter of weeds at the end of the relay intercropping period was better explained considering both legumes and wheat biomasses instead of legumes alone. In late autumn, 24 weeks after wheat harvest, weed biomass was largely reduced by the cover crops. Weed density and biomass reductions were correlated with cover crop biomass at wheat harvest and in late autumn. The presence of a cover crop also exhibited another positive effect by decreasing the density of spring-germinating annual weeds during the relay intercropping period.     

作物产量“三合结构”定量表达及高产分析

针对目前作物产量水平长期徘徊难以突破，产量分析理论缺乏量化指标体系，可操作指导作用小等问题，依据“三合结构”模式二级结构层各因素的关系，建立了“三合结构”定量表达式，并通过田间试验与模型模拟相结合的方法，对春玉米、夏玉米、水稻和冬小麦高产实例进行定量化分析，明确了限制产量进一步提高的关键因素，提出了高产突破的可能方向。结果表明，提高叶片平均净同化率（MNAR），改善群体的物质生产能力，是水稻产量进一步提升的关键；适当提高平均叶面积指数（MLAI）或经济系数（HI）可能会进一步增加冬小麦产量；春玉米籽粒产量主要伴随着MLAI和单位面积穗数（EN）的增加而提高，其实质是平均作物生长率（MCGR）的提高增加了单位面积上总粒数（TGN）。进一步研究确定了“三合结构”定量表达式参数间的函数关系式，通过公式代换可推导出某一参数与目标参数的函数关系。作物产量“三合结构”定量表达式的建立为作物群体定量化研究提供了新的思路和方法，有助于全面掌握群体参数变化与产量形成的定量关系，为指导作物生产进行有效的技术调控提供依据。